Editing Glucose (section)

===Glucose degradation===
{{Main|Glycolysis|Pentose phosphate pathway}}
[[File:Glucose metabolism.svg|thumb|Glucose metabolism and various forms of it in the process.{{pb}}Glucose-containing compounds and [[isomer]]ic forms are digested and taken up by the body in the intestines, including [[starch]], [[glycogen]], [[disaccharide]]s and [[monosaccharide]]s.{{pb}}Glucose is stored in mainly the liver and muscles as glycogen. It is distributed and used in tissues as free glucose.]]

In humans, glucose is metabolized by glycolysis<ref>{{Cite journal |doi=10.1042/BSR20160385 |pmc=5293555 |pmid=27707936|year=2016 |last1=Adeva-Andany |first1=M. M. |title=Liver glucose metabolism in humans |journal=Bioscience Reports |volume=36 |issue=6 |pages=e00416 |last2=Pérez-Felpete |first2=N. |last3=Fernández-Fernández |first3=C. |last4=Donapetry-García |first4=C. |last5=Pazos-García |first5=C. }}</ref> and the pentose phosphate pathway.<ref name="Horton">H. Robert Horton, [[Laurence A. Moran]], K. Gray Scrimgeour, Marc D. Perry, J. David Rawn: ''Biochemie'' {{In lang|de}}. Pearson Studium; 4. aktualisierte Auflage 2008; {{ISBN|978-3-8273-7312-0}}; pp. 490–496.</ref> Glycolysis is used by all living organisms,<ref name="Garrett"/>{{rp|551}}<ref name="Hall">Brian K. Hall: ''Strickberger's Evolution''. Jones & Bartlett Publishers, 2013, {{ISBN|978-1-449-61484-3}}, p.&nbsp;164.</ref> with small variations, and all organisms generate energy from the breakdown of monosaccharides.<ref name="Hall" /> In the further course of the metabolism, it can be completely degraded via [[oxidative decarboxylation]], the [[citric acid cycle]] (synonym ''Krebs cycle'') and the [[respiratory chain]] to water and carbon dioxide. If there is not enough oxygen available for this, the glucose degradation in animals occurs anaerobic to lactate via lactic acid fermentation and releases much less energy. Muscular lactate enters the liver through the bloodstream in mammals, where gluconeogenesis occurs ([[Cori cycle]]). With a high supply of glucose, the metabolite [[acetyl-CoA]] from the Krebs cycle can also be used for [[fatty acid synthesis]].<ref>{{Cite journal |doi=10.1007/s00125-016-3940-5|pmid=27048250|year=2016|last1=Jones|first1=J. G.|title=Hepatic glucose and lipid metabolism|journal=Diabetologia|volume=59|issue=6|pages=1098–103|doi-access=free}}</ref> Glucose is also used to replenish the body's glycogen stores, which are mainly found in liver and skeletal muscle. These processes are [[Hormone|hormonally]] regulated.

In other living organisms, other forms of fermentation can occur. The bacterium ''[[Escherichia coli]]'' can grow on nutrient media containing glucose as the sole carbon source.<ref name=Voet/>{{rp|59}} In some bacteria and, in modified form, also in archaea, glucose is degraded via the [[Entner-Doudoroff pathway]].<ref>{{cite journal | last1 = Entner | first1 = N. | last2 = Doudoroff | first2 = M. | year = 1952 | title = Glucose and gluconic acid oxidation of Pseudomonas saccharophila | journal = [[J Biol Chem]] | volume = 196 | issue = 2| pages = 853–862 | doi = 10.1016/S0021-9258(19)52415-2 | pmid = 12981024 | doi-access = free }}</ref> With glucose, a mechanism for [[gene regulation]] was discovered in ''E. coli'', the [[catabolite repression]] (formerly known as ''glucose effect'').<ref name="PMID29330542">{{cite journal | vauthors = Ammar EM, Wang X, Rao CV | title = Regulation of metabolism in Escherichia coli during growth on mixtures of the non-glucose sugars: arabinose, lactose, and xylose | journal = Scientific Reports | volume = 8 | issue = 1 | pages = 609 | date = January 2018 | pmid = 29330542 | pmc = 5766520 | doi = 10.1038/s41598-017-18704-0 | bibcode = 2018NatSR...8..609A | url = | issn = }}</ref>

Use of glucose as an energy source in cells is by either aerobic respiration, anaerobic respiration, or fermentation.<ref name="sil"/> The first step of glycolysis is the [[phosphorylation]] of glucose by a [[hexokinase]] to form [[glucose 6-phosphate]]. The main reason for the immediate phosphorylation of glucose is to prevent its diffusion out of the cell as the charged [[phosphate]] group prevents glucose 6-phosphate from easily crossing the [[cell membrane]].<ref name="sil">{{cite journal|last1=Bonadonna|first1=Riccardo C|last2=Bonora|first2=Enzo|last3=Del Prato|first3=Stefano|last4=Saccomani|first4=Maria|last5=Cobelli|first5=Claudio|last6=Natali|first6=Andrea|last7=Frascerra|first7=Silvia|last8=Pecori|first8=Neda|last9=Ferrannini|first9=Eleuterio|last10=Bier|first10=Dennis|last11=DeFronzo|first11=Ralph A|last12=Gulli|first12=Giovanni|title=Roles of glucose transport and glucose phosphorylation in muscle insulin resistance of NIDDM|journal=Diabetes|date=July 1996|volume=45|issue=7|pages=915–25|doi=10.2337/diab.45.7.915|pmid=8666143|s2cid=219249555|url=http://diabetes.diabetesjournals.org/content/45/7/915.full-text.pdf |archive-url=https://web.archive.org/web/20170306131309/http://diabetes.diabetesjournals.org/content/45/7/915.full-text.pdf |archive-date=6 March 2017 |url-status=live|access-date=5 March 2017}}</ref> Furthermore, addition of the high-energy phosphate group [[Activation#Biochemistry|activates]] glucose for subsequent breakdown in later steps of glycolysis.<ref>{{cite web | url=https://go.drugbank.com/drugs/DB09341 | title=Glucose | access-date=18 March 2024 | archive-date=5 December 2023 | archive-url=https://web.archive.org/web/20231205120936/https://go.drugbank.com/drugs/DB09341 | url-status=live }}</ref>

In anaerobic respiration, one glucose molecule produces a net gain of two ATP molecules (four ATP molecules are produced during glycolysis through substrate-level phosphorylation, but two are required by enzymes used during the process).<ref>{{citation | title = Medical Biochemistry at a Glance @Google books | url = https://books.google.com/books?id=9BtxCWxrWRoC&pg=PA52 | year = 2006 | page = 52 | publisher = Blackwell Publishing | isbn = 978-1-4051-1322-9 | url-status = live | archive-url = https://web.archive.org/web/20180223145046/https://books.google.com/books?id=9BtxCWxrWRoC&pg=PA52 | archive-date = 23 February 2018 }}</ref> In aerobic respiration, a molecule of glucose is much more profitable in that a maximum net production of 30 or 32 ATP molecules (depending on the organism) is generated.<ref>{{citation|title=Medical Biochemistry at a Glance @Google books|url=https://books.google.com/books?id=9BtxCWxrWRoC&pg=PA50|page=50|year=2006|archive-url=https://web.archive.org/web/20180223145046/https://books.google.com/books?id=9BtxCWxrWRoC&pg=PA50|publisher=Blackwell Publishing|isbn=978-1-4051-1322-9|archive-date=23 February 2018|url-status=live}}</ref>

{{GlycolysisGluconeogenesis_WP534|highlight=Glucose}}

[[Tumor]] cells often grow comparatively quickly and consume an above-average amount of glucose by glycolysis,<ref>{{Cite journal |doi=10.1097/MCO.0b013e32833a5577 |pmid=20473153|year=2010|last1=Annibaldi|first1=A.|title=Glucose metabolism in cancer cells|journal=Current Opinion in Clinical Nutrition and Metabolic Care|volume=13|issue=4|pages=466–70|last2=Widmann|first2=C.|s2cid=205782021}}</ref> which leads to the formation of lactate, the end product of fermentation in mammals, even in the presence of oxygen. This is called the [[Warburg effect (oncology)|Warburg effect]]. For the increased uptake of glucose in tumors various SGLT and GLUT are overly produced.<ref>{{Cite journal |doi=10.1016/j.bbcan.2012.12.004|pmid=23266512|year=2013|last1=Szablewski|first1=L.|title=Expression of glucose transporters in cancers|journal=Biochimica et Biophysica Acta (BBA) - Reviews on Cancer|volume=1835|issue=2|pages=164–9}}</ref><ref>{{Cite journal |doi=10.1097/CCO.0b013e328356da72 |pmid=22913968|year=2012|last1=Adekola|first1=K.|title=Glucose transporters in cancer metabolism|journal=Current Opinion in Oncology|volume=24|issue=6|pages=650–4|last2=Rosen|first2=S. T.|last3=Shanmugam|first3=M.|pmc=6392426}}</ref>

In [[yeast]], ethanol is fermented at high glucose concentrations, even in the presence of oxygen (which normally leads to respiration rather than fermentation). This is called the [[Crabtree effect]].

Glucose can also degrade to form carbon dioxide through abiotic means. This has been demonstrated to occur experimentally via oxidation and hydrolysis at 22&nbsp;°C and a pH of 2.5.<ref>{{cite journal |last1=Schümann |first1=U. |last2=Gründler |first2=P. |title=Electrochemical degradation of organic substances at PbO2 anodes: Monitoring by continuous CO2 measurements |journal=Water Research |date=September 1998 |volume=32 |issue=9 |pages=2835–2842 |doi=10.1016/s0043-1354(98)00046-3 }}</ref>